107th Congress

The Ideological Structure of Congressional Voting

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Overheads 10 September 2002

Overheads 12 September 2002

Overheads 17 and 19 September 2002

The Spatial Model of Voting

Figures From Poole and Rosenthal, Chapter 2

Redistricting Example

The 107^th Congress and the Iraq War Resolution

The Polarization of the Congressional Parties

In the Spatial maps below R indicates the ideal point of a Republican, S indicates the ideal point of a Southern Democrat (11 states of the Confederacy plus Kentucky and Oklahoma), and D indicates the ideal point of a Northern Democrat (all other states). In each image the House is shown in the left panel and the Senate is shown in the right panel. The configurations are of two-dimensional DW-NOMINATE scores. Note that the second dimension weight has not been used so that the spatial maps are easier to read. The Congressional District maps are from the VOTEVIEW for WINDOWS software that can be downloaded for free from this website. In the U.S. maps blue indicates Republican control and red indicates Democratic control.

The two chambers are very similar in their patterns over time. In the latter part of the New Deal voting on minimum wages (the Fair Labor Standards Act) opened up a split between the northern and southern wings of the Democratic party. During World War II, voting on issues related to the right of Blacks to vote in federal elections exacerbated the split. This split manifested itself as a second basic dimension in Congressional voting that largely captured voting on Civil Rights related issues. However, the split within the Democratic party also resulted in the Southern Democrats becoming more conservative on the first basic left-right/liberal-conservative dimension. (See Congress: A Political-Economic History of Roll Call Voting, Chapter 5 and Income Redistribution and the Realignment of American Politics [joint with Nolan McCarty, 1997, AEI Press] for an explanation).

Southern Democrats move to the right in both chambers on the first (liberal-conservative) dimension until just after the Civil Rights era of the mid to late 1960s and then begin moving back to the left during the 1970s and 1980s. Republicans shift to the left from the late 1940s and then reverse course after the Civil Rights era. Republicans in both chambers have been moving to the right since the late 1970s.

The gap between the Northern and Southern Democrats on the second dimension begins to close after the passage of the Civil Rights legislation in the 1960s. By the late 1980s the gap had largely disappeared and was no longer of great importance.